A battery apparatus includes a plurality of secondary batteries and when necessary discharges electricity charged in the secondary batteries. For example, the battery apparatus discharges, in the daytime, electricity charged during nighttime when the power rates are low, or discharges, in the nighttime, electricity charged by solar power generation during the daytime. Also, the battery apparatus discharges, at the time of power stoppage, electricity charged before the power stoppage.
Conventionally, in ordinary cases, a battery apparatus such as described above is installed in a factory, a business company's office or the like. In recent years, such a battery apparatus has come to be installed in ordinary houses.
As secondary batteries, film-sheathed batteries are ordinarily provided in a battery apparatus. A film-sheathed battery includes battery elements: positive electrode plates and negative electrode plates alternately stacked via separators. These battery elements are enclosed together with an electrolyte in a sheath film such as a laminated film.
In Patent Literature 1, a battery apparatus including a lithium-ion battery as a film-sheathed battery is described. The battery apparatus described in Patent Literature 1 includes a casing in rectangular block form made of metal plates. The internal space of the casing is partitioned into left and right spaces by a wall. In the right space, a lithium-ion battery having a plurality of cells integrally packed in a box and a lithium-ion battery filling unit are disposed. In the left space, an alternate current power supply controller for supplying alternating current power from the lithium-ion battery is disposed.